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This is a process that creates a skin and core material
arrangement in a molded part. The skin material is injected
first into the mold cavity, and is immediately followed by a
core material. As the skin material flows into the cavity, the
material next to the cavity walls freezes and material flows
down a center channel. When the core material enters it
displaces the skin material in the center of the channel by
pushing the skin ahead. As it flows ahead it continues to freeze
on the walls producing the skin layer Machine Based
Co-Injection
The Co-Injection process requires two injection/processing
units. The units generally inject material through a manifold
located at the end of the injection barrels. The manifold ports
the two melt streams into a centrally located nozzle. The
machine controls the injection units to achieve a skin-core-skin
flow sequence through the manifold into the mold. Last skin flow
is needed to clear the short nozzle section of core material and
to seal the gate area with skin. This arrangement can be used on
any single or multiple cavity, conventional cold runner mold.
Mold Based Co-Injection
This same process can be achieved on a hot runner mold by
utilizing a hot runner system from Incoe Corporation of Troy
Michigan. This system, sometimes identified as "Mold Based
Co-Injection", still utilizes two injection units. The two melt
streams are directed into the mod via separate channels. These
two channels remain separate until they reach the gate area of
the part. At this point they flow through a nozzle arrangement
similar to the normal co-injection manifold.
Co-Injection Benefits
- Lower Cost Parts
- Higher Strength Core
- Sound Absorption Core
- Reduced Cooling Time for Lower Temperature Core
- Improved Aesthetic Qualities
- Combined Property Characteristics
Co-Injection Features of a Milacron Machine
- Independent Co-Injection Manifold
- Easy Purging Of Individual Barrels and Manifold.
- Reversible Manifold for Optimizing Barrel Capacity with
Core %.
- Active Split ScreensTM for Viewing Multiple
Screens At Once.
- Control Sequences for Utilizing in Mold Co-Injection
Manifolds.
- Flexible Manifold Design for Machine or Mold Based
Co-Injection.
Applications:
- Foamed Core for reduced weight and noise transmission
- Glass filled cores for improved physical properties
- Low cost core for cost savings.
- High gloss skin material over structural core material for
combination of aesthetic and structural properties.
- Post Consumer Recycled material in core. Environmental
friendly.
- Post Industrial recycled Material in core
- Reground painted parts recycled into core.
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